Precision scale



July 4, 1944.4 E, D, HURLEY 2,352,838

PRECISION SCALE Filed sept. is, 1945 ngz INVENToR. D. HUIELE Y B ELA/El? atented July 4, 1944 UNITED STATES PATENT oFFicE PRECISION SCALE Elmer D. Hurley, Memphis, Tenn. Application september 1a, 1943, serial No. 502,125 (c1. .a3-103) 2 Claims.

lThis invention relates to improvements in scales through which direct measurements, or halved divisions of. such measurements, particularly adapted to effect the setting f the compass, au in drawing circles of certain diameter can be made.

'Ihe objects of the invention are:

To provide a scale through which extremely small variations in length may readily and accurately be measured; and

To further provide such a scale through which any given measurement may be halved, as in obtaining directlyvthe radius of a circle of known diameter.

The means bywhich these and other objects are accomplished, and the method of their accomplishment, will readily be understood from the following specification upon reference to the accompanying drawing, in which:

Fig. 1 is a face view of the scale, a portion only of the measuring blade being shown.

Fig. 2 is an end elevation of the head and the same portion of the blade; and

Fig. 3 a. fragmentary section transversely to the head and the longer blade, taken as on the line III-III of Fig. 1, showing on an enlarged scale the way in which the blade is preferably slidably secured to the head.`

Referring now to the drawing in which the various parts are indicated by numerals:

II is a head, which may be of any desired length, and is marked with 100 equally spaced graduations I3 at right angles to its lower edge I2, every tenth, oras here show'n, fth graduation preferably being made heavier, in usual manner, and the graduations being marked from to 100, in suitable manner.

The lower portion of this head is divided by longitudinal markings I1, I'IA. HB, which are spaced uniformly apart by increments, which have no necessary relation to the length increments, each increment being one tenth of the principal unit of length, which is to be used, this unit usually being one inch and hereinafter being so referred to, so that these lines, in such case, are uniformly one tenth of an inch apart. The upper of these lines I1A are marked 0 on the head, and being the base for length measurements. This lower portion of the head may be of any desired depth, as the six tenths here shown. From the intersection of the base line I'IA, with the zero division IBA, the upper edge of the head diverges and increases the head depth by the exact amount of one inch at the one hundredth division ISB, suclength from left to right by increments, each a one hundredth of an inch and the respective lengths being marked along the lower edge of the head in hundredths.

Cooperating with this head is a shiftable blade I9 which extends truly at right angles from the head and is shiftable along the'head to any desired position, this location in use being entirely governed by the measurement which it is desired to make. The blade I9 is preferably provided with a headed tenon 2| which closely, but slidably engages in a complementary groove extending throughout the length of the head. Preferably the blade is of slightly greater thickness than the head, in order that when the 'blade l's positioned to make a measurement on a flat surface and is firmly held thereagainst the head may be readily shifted.'

For convenience in cutting the groove, the head may be split into two portions IIA, IIB and thse portions, after the groove be cut, be secured together as by rivets 23, or otherwise as by gluing, welding or brazing, depending on the materials used.

The blade I9 has divisions 21 marked along its opposite edges, these divisions comprising main divisions spaced uniformly apart at the desired unit distance, here one inch, and marked by designating numbers l, 2., 3, etc., depending on the length of blade used, and intermediate divisions, each one tenth of an inch.

The first of these main divisions 21A, marked "1 on ,the blade, is at such distance below the bottom edge of the head' that it is exactly one inch from the naught longitudinal division I'IA of the head, in the present instance this being four minor divisions or tenths, and additional main divisions are at equal intervals of one inch and marked 2, 3, etc., these comprising the main meascessive intermediate. divisions thus increasing in urement divisions of the scale and being subdivided into tenths.

The blade is also marked with a longitudinal line 29, preferably along the center of the blade,`

which is transversely intersected at the main and ve tenths, or hall. principal unit intervals, a's at 3|, and designated by the smaller-numerals 2, '3; 4, 5, 6, 7, etc., these latter divisions being for obtaining radii of circles -of given diameter. To cooperate compass with the blade for this purpose, the upper portion` of the head carries an additionalV longitudinal line 33, which extends from the intersection of the zero vertical and horizontal divisions VIilli, I'IA and diverges from the horizontal division I'IA to an intersection with the 109 vertical division I3B, halving the edge divergences at each intermediate division. It will here be particularly noted that the horizontal division line II of the head is the base for determining in connection with the diverging line 33 the radii of circles under one inch in diameter and the five tenths line 11B, the similar base for circle radii between one and ltwo inches, the width six tenths of the'lower portion of. the head, and

number of inches shown on the blade and the number of hundredths shown on the head.

In Fig. 2, if the measurement being made is of a line extending from the three inch mark and along the left hand edge of the blade and the head has been shifted so that its upper edge is at the. opposite end of the line, the length shown is in. fact any other width chosen other than five tenths insuring that the measurement be not made from the joint line between the head and blade. For circles over two inches the centers Il on the blade are used in connection with the line 33.

In using the device for establishing radii for circles less than one inch in diameter, the compass center ispreferably set on the base line IIA of the head at its intersection with the hundredths line indicatingthe diameter of the circle,

and the scribing point is set on the intersection of the .same hundredths line with the line 33 and the setting obtained. i

If the circle be over .one and less than two inches, the measurements are still on the head only and the`-compass center is set on the base line llB at its intersection with the desired hundredth line and the scribing point set on the intersection of the same hundredth line and the line 33 and the setting obtained.

If the circle be of greater diameter than two inches, the blade must 'also be used. In such case,the blade is shifted until the line 29 coincides with that one of the head division lines which indicates the number of one hundredths over and above even inches, the center of the comthree inches and six hundred and forty-five thousandths, whereas, if the right hand edge of the blade is along the line to be measured and the head hasbeen properly shifted, the measurement from the three inch'mark indicates a length of three inches and seven hundred and seventy-five thousandths.l

It will be understood that the hundredth divisions on the head may be further subdivided into thousandths if desired.

I claim:

`l. A precision scale comprising an elongated head, and an elongated blade, slidably secured at4 right angles to one edge of said head for manual shifting therealong, said head being longitudinally divided into one hundred equal increments in- I, dicated by markings at right angles to its said pass is placed on that center Il indicating even i inches of diameter, and the scribing point on the intersection of the hundredths division line and the line 33, giving the desired radius for the circle.

. As an example, it is assumed that it is desired 1y thereof parallel with said edge, and dividedv to establish a compass setting to draw a circle I 2.71 inches i`n diameter.

The blade I9 has been l shiiteiiimtii the line 2s thereon coincides with the seventy-one hundredths mark on the head. If the center of the compass be now set at the center marking 3|, corresponding to two inches, i

y and the scribing point of the compass be moved to the point at which the seventy-one hundredths l line crosses the line 33, the proper radius for a two and seventy-one hundredths circle has been set. Without shift of the blade, additional compass settings may similarly be made for any other number of inches, plus seventy-one hundredths,

but for each change in hundredths, .blade shift wmust be made. A

In using the device for making measurements, one or the other of Athe edges of the blade of the scale is laid along the line to be measured with an even inch division mark at one end of the measurement to be made, the blade is hel-d firmly against the surface on which the to be measured line exists and the head is shifted forward or 1nwer edge and numbered at suitable intervals, and by a primary base line extending from end to end thereof parallel to` said edge, the opposite edge of said head diverging from the intersection of the zero of said markings and said base line vto the one hundredth said marking in an amount of one unit of length on said blade; said head having also a secondary longitudinal base line, bisecting the angle of divergence of said edge from said primary base line, said blade having at least one of its edges divided into and marked at equal unit intervals of length, the rst said marking being at exactly one unit interval from said head base line, and a base line extending longitudinali crements indicated by markings at right angles to backward. as the casemay be, until the upper f edge ofthe head lis exactly on the opposite end of the line, the length of the line comprising the 'its .saidlower edge and numbered from 10 togl00 at intervals, and by a base line extending from end to end thereof parallel to said edge, the opposite edge of said head diverging from the intersection of the zero of said markings and said baseline to the one hundredth said marking in an amount of ten said increments; said blade having at least one of its edges divided into' "and marked at equal unit intervals of ten said increments, the' first. said marking being-atexactlyone unit` interval from said head base line.

Ehrmann.HURLEY. 

